Antacids: Calcium Carbonate and Magnesium Compounds
ANTACIDS- Classification and Mechanism of Action
INTRODUCTION
Antacids are defined as a substance, generally a base, which counteracts stomach acidity. The name antacid means anti-acid (against acid). Antacids are the primary treatment for ailments such as gastric reflux, gastritis, upset stomach and heartburn. Hydrochloric acid is secreted by the stomach to kill harmful organisms, aid digestion and activate digestive enzymes. Excess secretion of acid into stomach or impaired resistance by the lining of the stomach or reflux into the oesophagus may produce symptoms and the treatment of these symptoms is by reducing the acidity in the stomach.
CLASSIFICATION OF ANTACIDS
Antacids can be classified into two main classes based on the mechanism used to counteract the stomach's acidity. One class works by chemical neutralisation of gastric acid (absorbable antacids) and the other class acts by absorption of the acid (non-absorbable antacids). Antacids are sometimes even formulated with additional components such as dimethicone and alginic acid. They are not to be confused with gastric acid inhibitors such as cimetidine and ranitidine.
Absorbable Antacids
The absorbable antacids (chemical antacids) show the most rapid onset of action and provide faster relief of symptoms. However they may cause an "acid rebound", a condition whereby the gastric acid returns in greater concentration after the drug effect has ceased. Moreover, this class of antacids is not suitable for all patients owing to its components. For example, the usually high concentration of sodium bicarbonate present in these chemical antacids may be inappropriate for patients afflicted with hypertension or kidney failure.
Non Absorbable Antacids
The non-absorbable antacids though less prone to cause a rebound effect, have their fair share of pros and cons. The most obvious disadvantage would be that these antacids interfere with the absorption and action of other drugs. Moreover as
INTRODUCTION
Antacids are defined as a substance, generally a base, which counteracts stomach acidity. The name antacid means anti-acid (against acid). Antacids are the primary treatment for ailments such as gastric reflux, gastritis, upset stomach and heartburn. Hydrochloric acid is secreted by the stomach to kill harmful organisms, aid digestion and activate digestive enzymes. Excess secretion of acid into stomach or impaired resistance by the lining of the stomach or reflux into the oesophagus may produce symptoms and the treatment of these symptoms is by reducing the acidity in the stomach.
CLASSIFICATION OF ANTACIDS
Antacids can be classified into two main classes based on the mechanism used to counteract the stomach's acidity. One class works by chemical neutralisation of gastric acid (absorbable antacids) and the other class acts by absorption of the acid (non-absorbable antacids). Antacids are sometimes even formulated with additional components such as dimethicone and alginic acid. They are not to be confused with gastric acid inhibitors such as cimetidine and ranitidine.
Absorbable Antacids
The absorbable antacids (chemical antacids) show the most rapid onset of action and provide faster relief of symptoms. However they may cause an "acid rebound", a condition whereby the gastric acid returns in greater concentration after the drug effect has ceased. Moreover, this class of antacids is not suitable for all patients owing to its components. For example, the usually high concentration of sodium bicarbonate present in these chemical antacids may be inappropriate for patients afflicted with hypertension or kidney failure.
Non Absorbable Antacids
The non-absorbable antacids though less prone to cause a rebound effect, have their fair share of pros and cons. The most obvious disadvantage would be that these antacids interfere with the absorption and action of other drugs. Moreover as